// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/time/time.h"

#include <cmath>
#include <ios>
#include <limits>
#include <ostream>
#include <sstream>

#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/stringprintf.h"
#include "base/third_party/nspr/prtime.h"
#include "build/build_config.h"

namespace base {

// TimeDelta ------------------------------------------------------------------

// static
TimeDelta TimeDelta::Max()
{
    return TimeDelta(std::numeric_limits<int64_t>::max());
}

int TimeDelta::InDays() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int>::max();
    }
    return static_cast<int>(delta_ / Time::kMicrosecondsPerDay);
}

int TimeDelta::InHours() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int>::max();
    }
    return static_cast<int>(delta_ / Time::kMicrosecondsPerHour);
}

int TimeDelta::InMinutes() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int>::max();
    }
    return static_cast<int>(delta_ / Time::kMicrosecondsPerMinute);
}

double TimeDelta::InSecondsF() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<double>::infinity();
    }
    return static_cast<double>(delta_) / Time::kMicrosecondsPerSecond;
}

int64_t TimeDelta::InSeconds() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int64_t>::max();
    }
    return delta_ / Time::kMicrosecondsPerSecond;
}

double TimeDelta::InMillisecondsF() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<double>::infinity();
    }
    return static_cast<double>(delta_) / Time::kMicrosecondsPerMillisecond;
}

int64_t TimeDelta::InMilliseconds() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int64_t>::max();
    }
    return delta_ / Time::kMicrosecondsPerMillisecond;
}

int64_t TimeDelta::InMillisecondsRoundedUp() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int64_t>::max();
    }
    return (delta_ + Time::kMicrosecondsPerMillisecond - 1) / Time::kMicrosecondsPerMillisecond;
}

int64_t TimeDelta::InMicroseconds() const
{
    if (is_max()) {
        // Preserve max to prevent overflow.
        return std::numeric_limits<int64_t>::max();
    }
    return delta_;
}

namespace time_internal {

    int64_t SaturatedAdd(TimeDelta delta, int64_t value)
    {
        CheckedNumeric<int64_t> rv(delta.delta_);
        rv += value;
        return FromCheckedNumeric(rv);
    }

    int64_t SaturatedSub(TimeDelta delta, int64_t value)
    {
        CheckedNumeric<int64_t> rv(delta.delta_);
        rv -= value;
        return FromCheckedNumeric(rv);
    }

    int64_t FromCheckedNumeric(const CheckedNumeric<int64_t> value)
    {
        if (value.IsValid())
            return value.ValueUnsafe();

        // We could return max/min but we don't really expose what the maximum delta
        // is. Instead, return max/(-max), which is something that clients can reason
        // about.
        // TODO(rvargas) crbug.com/332611: don't use internal values.
        int64_t limit = std::numeric_limits<int64_t>::max();
        if (value.validity() == internal::RANGE_UNDERFLOW)
            limit = -limit;
        return value.ValueOrDefault(limit);
    }

} // namespace time_internal

std::ostream& operator<<(std::ostream& os, TimeDelta time_delta)
{
    return os << time_delta.InSecondsF() << "s";
}

// Time -----------------------------------------------------------------------

// static
Time Time::FromTimeT(time_t tt)
{
    if (tt == 0)
        return Time(); // Preserve 0 so we can tell it doesn't exist.
    if (tt == std::numeric_limits<time_t>::max())
        return Max();
    return Time(kTimeTToMicrosecondsOffset) + TimeDelta::FromSeconds(tt);
}

time_t Time::ToTimeT() const
{
    if (is_null())
        return 0; // Preserve 0 so we can tell it doesn't exist.
    if (is_max()) {
        // Preserve max without offset to prevent overflow.
        return std::numeric_limits<time_t>::max();
    }
    if (std::numeric_limits<int64_t>::max() - kTimeTToMicrosecondsOffset <= us_) {
        DLOG(WARNING) << "Overflow when converting base::Time with internal "
                      << "value " << us_ << " to time_t.";
        return std::numeric_limits<time_t>::max();
    }
    return (us_ - kTimeTToMicrosecondsOffset) / kMicrosecondsPerSecond;
}

// static
Time Time::FromDoubleT(double dt)
{
    if (dt == 0 || /*std::*/isnan(dt))
        return Time(); // Preserve 0 so we can tell it doesn't exist.
    return Time(kTimeTToMicrosecondsOffset) + TimeDelta::FromSecondsD(dt);
}

double Time::ToDoubleT() const
{
    if (is_null())
        return 0; // Preserve 0 so we can tell it doesn't exist.
    if (is_max()) {
        // Preserve max without offset to prevent overflow.
        return std::numeric_limits<double>::infinity();
    }
    return (static_cast<double>(us_ - kTimeTToMicrosecondsOffset) / static_cast<double>(kMicrosecondsPerSecond));
}

#if defined(OS_POSIX)
// static
Time Time::FromTimeSpec(const timespec& ts)
{
    return FromDoubleT(ts.tv_sec + static_cast<double>(ts.tv_nsec) / base::Time::kNanosecondsPerSecond);
}
#endif

// static
Time Time::FromJsTime(double ms_since_epoch)
{
    // The epoch is a valid time, so this constructor doesn't interpret
    // 0 as the null time.
    return Time(kTimeTToMicrosecondsOffset) + TimeDelta::FromMillisecondsD(ms_since_epoch);
}

double Time::ToJsTime() const
{
    if (is_null()) {
        // Preserve 0 so the invalid result doesn't depend on the platform.
        return 0;
    }
    if (is_max()) {
        // Preserve max without offset to prevent overflow.
        return std::numeric_limits<double>::infinity();
    }
    return (static_cast<double>(us_ - kTimeTToMicrosecondsOffset) / kMicrosecondsPerMillisecond);
}

int64_t Time::ToJavaTime() const
{
    if (is_null()) {
        // Preserve 0 so the invalid result doesn't depend on the platform.
        return 0;
    }
    if (is_max()) {
        // Preserve max without offset to prevent overflow.
        return std::numeric_limits<int64_t>::max();
    }
    return ((us_ - kTimeTToMicrosecondsOffset) / kMicrosecondsPerMillisecond);
}

// static
Time Time::UnixEpoch()
{
    Time time;
    time.us_ = kTimeTToMicrosecondsOffset;
    return time;
}

Time Time::LocalMidnight() const
{
    Exploded exploded;
    LocalExplode(&exploded);
    exploded.hour = 0;
    exploded.minute = 0;
    exploded.second = 0;
    exploded.millisecond = 0;
    return FromLocalExploded(exploded);
}

// static
bool Time::FromStringInternal(const char* time_string,
    bool is_local,
    Time* parsed_time)
{
    DCHECK((time_string != NULL) && (parsed_time != NULL));

    if (time_string[0] == '\0')
        return false;

    PRTime result_time = 0;
    PRStatus result = PR_ParseTimeString(time_string,
        is_local ? PR_FALSE : PR_TRUE,
        &result_time);
    if (PR_SUCCESS != result)
        return false;

    result_time += kTimeTToMicrosecondsOffset;
    *parsed_time = Time(result_time);
    return true;
}

// static
bool Time::ExplodedMostlyEquals(const Exploded& lhs, const Exploded& rhs)
{
    return lhs.year == rhs.year && lhs.month == rhs.month && lhs.day_of_month == rhs.day_of_month && lhs.hour == rhs.hour && lhs.minute == rhs.minute && lhs.second == rhs.second && lhs.millisecond == rhs.millisecond;
}

std::ostream& operator<<(std::ostream& os, Time time)
{
    Time::Exploded exploded;
    time.UTCExplode(&exploded);
    // Use StringPrintf because iostreams formatting is painful.
    return os << StringPrintf("%04d-%02d-%02d %02d:%02d:%02d.%03d UTC",
               exploded.year,
               exploded.month,
               exploded.day_of_month,
               exploded.hour,
               exploded.minute,
               exploded.second,
               exploded.millisecond);
}

// Local helper class to hold the conversion from Time to TickTime at the
// time of the Unix epoch.
class UnixEpochSingleton {
public:
    UnixEpochSingleton()
        : unix_epoch_(TimeTicks::Now() - (Time::Now() - Time::UnixEpoch()))
    {
    }

    TimeTicks unix_epoch() const { return unix_epoch_; }

private:
    const TimeTicks unix_epoch_;

    DISALLOW_COPY_AND_ASSIGN(UnixEpochSingleton);
};

static LazyInstance<UnixEpochSingleton>::Leaky
    leaky_unix_epoch_singleton_instance
    = LAZY_INSTANCE_INITIALIZER;

// Static
TimeTicks TimeTicks::UnixEpoch()
{
    return leaky_unix_epoch_singleton_instance.Get().unix_epoch();
}

TimeTicks TimeTicks::SnappedToNextTick(TimeTicks tick_phase,
    TimeDelta tick_interval) const
{
    // |interval_offset| is the offset from |this| to the next multiple of
    // |tick_interval| after |tick_phase|, possibly negative if in the past.
    TimeDelta interval_offset = (tick_phase - *this) % tick_interval;
    // If |this| is exactly on the interval (i.e. offset==0), don't adjust.
    // Otherwise, if |tick_phase| was in the past, adjust forward to the next
    // tick after |this|.
    if (!interval_offset.is_zero() && tick_phase < *this)
        interval_offset += tick_interval;
    return *this + interval_offset;
}

std::ostream& operator<<(std::ostream& os, TimeTicks time_ticks)
{
    // This function formats a TimeTicks object as "bogo-microseconds".
    // The origin and granularity of the count are platform-specific, and may very
    // from run to run. Although bogo-microseconds usually roughly correspond to
    // real microseconds, the only real guarantee is that the number never goes
    // down during a single run.
    const TimeDelta as_time_delta = time_ticks - TimeTicks();
    return os << as_time_delta.InMicroseconds() << " bogo-microseconds";
}

std::ostream& operator<<(std::ostream& os, ThreadTicks thread_ticks)
{
    const TimeDelta as_time_delta = thread_ticks - ThreadTicks();
    return os << as_time_delta.InMicroseconds() << " bogo-thread-microseconds";
}

// Time::Exploded -------------------------------------------------------------

inline bool is_in_range(int value, int lo, int hi)
{
    return lo <= value && value <= hi;
}

bool Time::Exploded::HasValidValues() const
{
    return is_in_range(month, 1, 12) && is_in_range(day_of_week, 0, 6) && is_in_range(day_of_month, 1, 31) && is_in_range(hour, 0, 23) && is_in_range(minute, 0, 59) && is_in_range(second, 0, 60) && is_in_range(millisecond, 0, 999);
}

} // namespace base
